Compact, high-efficiency accelerators driven by low-voltage solid-state amplifiers

ABSTRACT

A compact particle accelerator can include two or more cavities disposed along an axis of the particle accelerator, each of which is coupled to two or more drivers. The accelerator can also include a power supply coupled to the two or more drivers such that a particle beam traveling along the axis is accelerated. The power supply can be an interface with a commercial power outlet, battery power, or a combination thereof depending upon the use case. Example configurations of the accelerator include hand held or mobile devices that are capable of delivering up to and greater than a 1 MeV electron beam.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to and the benefit of U.S.Provisional Patent Application No. 62/425,025, filed on Nov. 21, 2016,the contents of which are incorporated herein by reference in itsentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The present invention was made with government support under ContractNo. DE-AC52-06NA25396 awarded by the U.S. Department of Energy/NationalNuclear Security Administration to Los Alamos National Security, LLC forthe operation of Los Alamos National Laboratory. The government hascertain rights in the invention.

FIELD

The present invention relates generally to the field of particleaccelerator, and more particularly to the field of high performance,compact particle accelerators (e.g., in hand held or mobile devices).

BACKGROUND

There is an ever increasing need to reduce the size, weight, cost andcomplexity of particle accelerators in applications beyond the usualhigh-energy physics, nuclear physics and synchrotron light sources wherethe accelerator designs have been largely based on the traditionallarge, complex, high-voltage, high-gradient designs. As the use ofparticle beams becomes more diversified and commonplace, the limitationsinherent within prior legacy designs are becoming more evident. In themedical field, for example, the availability of accelerators that can beused for imaging or therapeutic purposes is limited by their size andcost, and operational characteristics, such as whether the acceleratoris a cyclotron or a linac, power consumption (typically in the MW level)and cooling requirements (water cooling towers or liquid heliumrefrigerators). As such, these accelerators tend to be located incommunities and facilities that can support these constraints, such asmajor accelerator complexes with access to high-voltage electricalequipment, high-volume water cooling systems and/or heliumrefrigeration, major hospitals or large irradiation facilities for foodand mail sterilization. Medical applications of accelerators have beenpredominantly used for electron acceleration for radiationcancer-treatment therapy. Further proton-beam therapy has been provenvery efficacious in treating a variety of cancers with minimal sideeffects; however, proton-beam therapy is not as widely used as X-raytherapy for treating cancer. This is due to a $100M price tag for eachproton accelerator (either a cyclotron or a synchrotron) and the protonbeam delivering gantry system. As a result, only a handful of hospitalsin the US offer their patients the proton beam therapy option.Unfortunately, the need for advanced care far exceeds the ability toprovide it for those communities most in need. Most of the world'spopulation does not reside near a hospital with particle beam therapybased on traditional accelerator designs, thus that population is deniedthe most advanced medical care available.

Accordingly, there is a need in the art for a compact and robustparticle accelerator that can eliminate the structural and operationalconstraints on the provision of advanced medical care.

SUMMARY

A compact particle accelerator can include two or more cavities disposedalong an axis, with each of the cavities being powered by two or more RFdrivers. The accelerator can also include multiple cavities each ofwhich is coupled to two or more RF drivers such that a particle beamtraveling along the axis is accelerated. The RF drivers can be poweredwith a commercial power outlet, a low-voltage power supply, batterypower, or a combination thereof depending upon the use case. Exampleconfigurations of the accelerator include hand held or mobile devicesthat are capable of delivering a medically-usable beam power (e.g.,greater than 1 MeV particle beam energy), thereby distributing advancedmedical technologies to a large segment of the human population that hasyet to benefit from accelerator technology. Additional features andadvantages of the radiation generator of the embodiment are described indetail below with reference to the following drawings.

According to an embodiment of the present invention, there is provided aparticle accelerator including: two or more cavities disposed along anaxis that are driven independently by solid-state transistor radiofrequency (RF) sources; two or more independent RF drivers, each withits own phase and amplitude control, independent of the other RFdrivers; and a low-voltage power supply providing power to two or moreRF drivers.

Each of the two or more RF drivers may include a high electron mobilitytransistor (HEMT). Each of the two or more RF drivers may furtherinclude a phase shifter coupled to the HEMT. Each of the two or more RFdrivers may drive between 300 W and 500 W of RF power to each of the twoor more cavities.

Each of the two or more drivers may drive more than 300 W of power toeach of the two or more cavities. Each of the two or more drivers maydrive between 200 W and 400 W of RF power to each of the two or morecavities. Each of the two or more drivers may drive at least 350 W and400 W of RF power to each of the two or more cavities.

The power supply may include one or more batteries. The power supply mayinclude commercial power provided through a wall outlet.

The two or more cavities may include more than ten cavities. The two ormore cavities may include more than fifteen cavities. The two or morecavities may include more than twenty cavities. The two or more cavitiesmay include more than twenty-five cavities.

Each of the two or more cavities may include a resonant cavity thatresonates between 1 GHz and 6 GHz. Each of the two or more cavities mayinclude a resonant cavity that resonates at 5.1 GHz. Each of the two ormore cavities may include an accelerating gap distance defined by aratio of the velocity of a particle in the particle beam to the speed oflight.

The particle accelerator may include fifty five cavities and thirtybatteries to generate a 1 MeV electron beam. The particle acceleratormay be 1.25 m in length along the axis and weigh 30 kg.

The particle accelerator may include one hundred thirty eight cavitiesand seventy-five batteries to generate a 5 MeV electron beam. Theparticle accelerator may be 3.1 m in length along the axis of theparticle accelerator and weigh 108 kg.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and aspects of the present invention will beappreciated and understood with reference to the specification, claims,and appended drawings.

FIG. 1 is a schematic block diagram of a compact particle accelerator inaccordance with an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a compact particle accelerator inaccordance with an alternative embodiment of the present invention.

FIG. 3 is a cross-sectional diagram of a cavity of a compact particleaccelerator in accordance with an alternative embodiment of the presentinvention.

FIG. 4 is a graphical representation of a power curve of a component ofa compact particle accelerator in accordance with an alternativeembodiment of the present invention.

FIG. 5 is a graphical representation of a beam pulse shape of a compactparticle accelerator in accordance with an alternative embodiment of thepresent invention.

FIG. 6A is a graphical representation of a size/weight/power curve of acompact particle accelerator in accordance with an alternativeembodiment of the present invention.

FIG. 6B is a graphical representation of a power/energy curve forvarious power sources of a compact particle accelerator in accordancewith an alternative embodiment of the present invention.

FIG. 7A is a perspective view of an example embodiment of a compactparticle accelerator in accordance with an alternative embodiment of thepresent invention.

FIG. 7B is a perspective view of an example embodiment of a compactparticle accelerator in accordance with another alternative embodimentof the present invention.

DETAILED DESCRIPTION

As described herein, a compact particle accelerator can providesubstantially all of the benefits of a more traditionally configuredaccelerator, but with substantially reduced size, cost, and weight. Invarious alternative embodiments described herein, the compact particleaccelerator can be configured to be portable and/or handheld, thuspermitting the provision of certain advanced medical technologies inremote communities of need. The following description of the embodimentsof the invention is not intended to limit the invention to theseembodiments, but rather to enable any person skilled in the art to makeand use this invention.

As shown in FIG. 1, a compact particle accelerator 10 in accordance withan embodiment can include one or more cavities 30 disposed along an axisof the particle accelerator (or along a particle beam of the particleaccelerator) 24, each of the cavities 30 is coupled to one or more RFdrivers 18. The accelerator 10 can also include a power supply 22coupled to the one or more RF drivers 18 such that a particle beam 24traveling along the axis 24 is accelerated. In operation, theaccelerator 10 functions to increase the energy of an injected particlebeam to a medically-usable level, and to do so in a compact and portableform factor that removes prior use and design constraints of thetechnology. Depending upon the desired output and configuration, as wellas certain trade-offs and improvements in battery technologies, theaccelerator 10 can be configured as a hand held or mobile device that iscapable of delivering a medically-usable beam power (e.g., 1 MeVelectron beam), thereby distributing advanced medical technologies to alarge segment of the human population that has yet to benefit frommedical accelerator technology.

As shown in FIG. 1, the accelerator 10 can include one or more RFdrivers 18 that are coupled each to one or more cavities 30. The RFdrivers 18 function to drive RF power into each of the one or morecavities 30 such that a particle beam 24 passing through each of the oneor more cavities will receive an increase in total energy, as manifestedin a net acceleration of the particles within the particle beam 24. Inone variation of the accelerator 10, the one or more RF drivers caninclude a high electron mobility transistor (HEMT). A HEMT 18 caninclude any suitable custom or commercially available device that isconfigured to deliver the requisite voltage/wattage per cavity 30 in theaccelerator 10. Example HEMTs 18 can include, for example, a galliumnitride (GaN) HEMT, a wide-bandgap AlGaN/GaN HEMT, and a metamorphicHEMT (AlInAs, GaInAs), or any suitable combination thereof. In onealternative embodiment, the HEMT 18 includes a GaN device that isconfigured and/or designed to deliver power comparable to 370 W,corresponding to at least 20 keV energy acceleration per cavity 30 inthe accelerator 10.

As shown in FIG. 1, in alternative embodiments the accelerator 10 caninclude a phase shifter 20 coupled to one or more of the drivers 18. Thephase shifters 20 function to sequence, align, shift, modify, modulate,and/or control the phase of RF power delivered to each of the RF drivers18 prior to driving each of the cavities 30. The accelerator 10 can alsoinclude a low-level radio frequency (LLRF) controller 12, a preamp 14,and an amplifier 16 coupled to each other and coupled in parallel toeach of the one or more phase shifters 20. Alternatively, each of thephase shifters 20 can have its own LLRF controller 12 and preamp 14directly coupled in series, each being controlled by a separatecontroller that functions similarly to a circulator 16 or identically toa circulator 16.

As shown in FIG. 1, the accelerator 10 can also include a controller 40that is configured to control one or more aspects of the operation ofthe accelerator 10, including for example the phasing of the input powerinto the one or more drivers 18. In particular, the controller 40 can beconfigured to control the phasing of the input power by controlling atleast the one or more phase shifters 20, as well as the LLRF 12, preamp14, and/or the amplifier 16. The controller 40 is configured to adapt tooperating conditions of the accelerator 10 such that performance isimproved or optimized during operation. Suitable feedback measures ofoperation can include for example field gradients within the one or morecavities 30, the failure of any of the one or more cavities 30, spacingor other geometrical aspects of the one or more cavities 30, presence orchanges in an external electromagnetic field, electromagneticinterference, charged/heavy particle interference, or any other suitablemeasure that can impact the performance of the one or more cavities 30.The controller 40 can detect the phase and amplitude signals from one ormore sensors and use a smart algorithm to provide the optimizedintegral, proportional and differential signals to the LLRF 12. Those ofskill in the art will readily appreciate that one or more of thesecomponents can be substituted for one or more functionally equivalentelectronic and/or controller components without departing from thespirit of the present specification.

As shown in FIG. 1, the accelerator 10 can also include and/or becoupled to a power supply 22. The power supply 22 functions to provideelectrical power to the one or more RF drivers 18 such that the lattercan drive an acceleration of the particle beam 24. In one variation ofthe accelerator 10, the power supply 22 can be an integral component ofthe accelerator 10, such as a portable power supply 22 configured forexample as a battery. In another variation of the accelerator 10 of theembodiment, the power supply 22 can be a standard electrical outlet thatone would find in a residential or commercial setting that provides therequisite voltage to power the one or more drivers 18. In such avariation of the accelerator 10, the power supply 22 is not integralwith the accelerator 10, but rather the accelerator 10 can includecomponents to couple with the power supply (e.g., power cord, wallinterface) as well as components to receive, convert, shield, and/ortransmit the received power (e.g., AC/DC converter, EMF shielding,circuit breaker) to the one or more drivers 18.

In still other variations of the accelerator 10, the power supply 22 caninclude both an integrated delivery system (battery) as well as acommercial power conversion system as described herein. For example, avariation of the power supply 22 can include a bank or block ofrechargeable batteries as well as an interface for drawing downcommercial power for the purpose of either recharging the rechargeablebatteries and/or powering the accelerator 10.

According to some embodiments, the power supply 22 can provide acommercially available voltage to the one or more drivers 18.Alternatively, the power supply 22 can provide approximately between 40Vand 60V (e.g., between 40V and 60V) to the one or more drivers 18. Instill other variations, the power supply 22 can provide approximately50V (e.g., 50V) to the one or more drivers 18, either as an integratedbattery pack, a commercial power converter, or a combination thereof inthe form of one or more rechargeable batteries. As those of skill in theart will appreciate, the exact voltage to be supplied by a suitablepower supply 22 can depend entirely upon the desired power output of theone or more drivers 18, the power amplification efficiency of the one ormore drivers 18, as well as the size and weight design specifications ofthe desired accelerator. It should be understood that the foregoingdescription is illustrative of one set of design parameters, and thatmaterial and functional improvements in ancillary technologies relatingto batteries and drivers can readily result in even lower power, higherefficiency compact acceleration.

As shown in FIG. 1, each of the one or more drivers 18 of theaccelerator 10 drives power to each of the one or more cavities 30 toincrease the resultant energy in the particle beam 24. In one variationof the accelerator 10, each of the one or more drivers 18 can drivebetween approximately 300 W and 500 W (e.g., between 300 W and 500 W) ofpower to each of the one or more cavities 30. In another variation ofthe accelerator 10, each of the one or more drivers 18 can drive morethan 300 W of power to each of the one or more cavities 30. In yetanother variation of the accelerator 10, each of the one or more drivers18 can drive between approximately 200 W and 400 W (e.g., between 200 Wand 400 W) of power to each of the one or more cavities 30. In stillanother variation of the accelerator 10, each of the one or more drivers18 can drive between approximately 350 W and 400 W (e.g., between 350 Wand 400 W) of power to each of the one or more cavities 30. In stillanother variation of the accelerator 10, each of the one or more drivers18 can have a variable, non-identical, or customizable drive outputbased upon the configuration, output, physical design, or geometry ofthe accelerator 10. Those of skill in the art will readily appreciatethat one or more types of driver 18 can be used, for example differenttypes of HEMTs, and therefore one can readily design an accelerator thatincludes one or more drivers 18 each having a different, variable, orotherwise optimized output power based upon the design specifications ofthe accelerator 10.

As shown in FIG. 2, a compact particle accelerator 110 in accordancewith an embodiment can include one or more cavities 130 disposed alongan axis 124, each of which is coupled to one or more drivers 118. Theaccelerator 110 can also include a frequency tuner 132 coupled to thepicomotors attached to one or more cavities 130. The function of thefrequency tuner and picomotors is to adjust the resonance frequency ofone or more cavities 130 such that a particle beam 124 traveling alongthe axis 124 is accelerated continuously. In operation, the accelerator110 functions to increase the energy of an injected particle beam to amedically-usable level, and to do so in a compact and portable formfactor that removes prior use and design constraints of the technology.Depending upon the desired output and configuration, as well as certaintrade-offs and improvements in battery technologies, the accelerator 110can be configured as a hand held or mobile device that is capable ofdelivering a medically-usable beam power (e.g., 1 MeV electron beam),thereby distributing advanced medical technologies to a large segment ofthe human population that has yet to benefit from medical acceleratortechnology.

As shown in FIG. 2, the accelerator 110 can include one or more drivers118 that are coupled each to one or more cavities 130. The drivers 118function to drive power into each of the one or more cavities 130 suchthat a particle beam 124 passing through each of the one or morecavities will receive an increase in total energy, as manifested in anet acceleration of the particles within the particle beam 124. In onevariation of the accelerator 110, the one or more drivers can include ahigh electron mobility transistor (HEMT). A HEMT 118 can include anysuitable custom or commercially available device that is configured todeliver the requisite voltage/wattage per cavity 130 in the accelerator110. Example HEMTs 118 can include, for example, a gallium nitride (GaN)HEMT, a wide-bandgap AlGaN/GaN HEMT, and a metamorphic HEMT (AlInAs,GaInAs), or any suitable combination thereof. In one alternativeembodiment, the HEMT 118 includes a GaN device that is configured and/ordesigned to deliver power comparable to 370 W, corresponding to at least20 keV energy acceleration per cavity 130 in the accelerator 110.

As shown in FIG. 2, in alternative embodiments the accelerator 110 caninclude a phase shifter 120 coupled to one or more of the drivers 118.The phase shifters 120 function to sequence, align, shift, modify,modulate, and/or control the delivery of power to each of the drivers118 prior to driving each of the cavities 130. The accelerator 110 canalso include a microwave oscillator 112 coupled to each of the one ormore phase shifters 120. Alternatively, each of the phase shifters 120can have its own microwave oscillator 112 directly coupled thereto.

As shown in FIG. 2, the accelerator 10 can also include a controller 140that is configured to control one or more aspects of the operation ofthe accelerator 110, including for example the phasing of the inputpower into the one or more drivers 118. In particular, the controller140 can be configured to control the phasing of the input power bycontrolling at least the one or more phase shifters 120, as well as themicrowave oscillator 112. The controller 140 is configured to adapt tooperating conditions of the accelerator 110 such that performance isoptimized during operation. Suitable feedback measures of operation caninclude for example field gradients within the one or more cavities 130,the failure of any of the one or more cavities 130, spacing or othergeometrical aspects of the one or more cavities 130, presence or changesin an external electromagnetic field, electromagnetic interference,charged/heavy particle interference, or any other suitable measure thatcan impact the performance of the one or more cavities 130. Thecontroller 140 can detect the phase and amplitude signals from one ormore sensors and use a smart algorithm to provide the improved oroptimized integral, proportional and differential signals to themicrowave oscillator 112. The controller 140 can also provide signal tothe frequency tuner 132 to adjust the resonance frequency of one or morecavities 130 to achieve continuous energy gain from one cavity to thenext. Those of skill in the art will readily appreciate that one or moreof these components can be substituted for one or more functionallyequivalent electronic and/or controller components without departingfrom the spirit of the present specification.

As shown in FIG. 1, the accelerator 110 can also include and/or becoupled to a power supply 122. The power supply 122 functions to provideelectrical power to the one or more drivers 118 such that the latter candrive an acceleration of the particle beam 124. In one variation of theaccelerator 110, the power supply 122 can be an integral component ofthe accelerator 110, such as a portable power supply 122 configured forexample as a battery. In another variation of the accelerator 110 of theembodiment, the power supply 122 can be a standard electrical outletthat one would find in a residential or commercial setting that providesthe requisite voltage to power the one or more drivers 118. In such avariation of the accelerator 110, the power supply 122 is not integralwith the accelerator 110, but rather the accelerator 110 can includecomponents to couple with the power supply (e.g., power cord, wallinterface) as well as components to receive, convert, shield, and/ortransmit the received power (e.g., AC/DC converter, EMF shielding,circuit breaker) to the one or more drivers 118.

In still other variations of the accelerator 110, the power supply 122can include both an integrated delivery system (battery) as well as acommercial power conversion system as described herein. For example, avariation of the power supply 122 can include a bank or block ofrechargeable batteries as well as an interface for drawing downcommercial power for the purpose of either recharging the rechargeablebatteries and/or powering the accelerator 110.

According to some embodiments, the power supply 122 can provide acommercially available voltage to the one or more drivers 118.Alternatively, the power supply 122 can provide approximately between40V and 60V (e.g., between 40V and 60V) to the one or more drivers 118.In still other variations, the power supply 122 can provideapproximately 50V (e.g., 50V) to the one or more drivers 118, either asan integrated battery pack, a commercial power converter, or acombination thereof in the form of one or more rechargeable batteries.As those of skill in the art will appreciate, the exact voltage to besupplied by a suitable power supply 122 can depend entirely upon thedesired power output of the one or more drivers 118, the poweramplification efficiency of the one or more drivers 118, as well as thesize and weight design specifications of the desired accelerator. Itshould be understood that the foregoing description is illustrative ofone set of design parameters, and that material and functionalimprovements in ancillary technologies relating to batteries and driverscan readily result in even lower power, higher efficiency compactacceleration.

As shown in FIG. 1, each of the one or more drivers 118 of theaccelerator 110 drives power to each of the one or more cavities 130 toincrease the resultant energy in the particle beam 124. In one variationof the accelerator 110, each of the one or more drivers 118 can drivebetween approximately 300 W and 500 W (e.g., between 300 W and 500 W) ofpower to each of the one or more cavities 30. In another variation ofthe accelerator 110, each of the one or more drivers 118 can drive morethan 300 W of power to each of the one or more cavities 130. In yetanother variation of the accelerator 110, each of the one or moredrivers 118 can drive between approximately 200 W and 400 W (e.g.,between 200 W and 400 W) of power to each of the one or more cavities130. In still another variation of the accelerator 110, each of the oneor more drivers 118 can drive between approximately 350 W and 400 W(e.g., between 350 W and 400 W) of power to each of the one or morecavities 130. In still another variation of the accelerator 110, each ofthe one or more drivers 118 can have a variable, non-identical, orcustomizable drive output based upon the configuration, output, physicaldesign, or geometry of the accelerator 110. Those of skill in the artwill readily appreciate that one or more types of driver 118 can beused, for example different types of HEMTs, and therefore one canreadily design an accelerator that includes one or more drivers 118 eachhaving a different, variable, or otherwise optimized output power basedupon the design specifications of the accelerator 110.

As shown in FIG. 3, the accelerator 10 can include one or more cavities30 each connected to one of the one or more drivers 18. Each of thecavities 30 is oriented about an axis 24 that is coincident or collinearwith a particle beam 24 as shown in FIG. 1. The cavities 30 function tocontain, direct, amplify, increase, resonate, and/or accelerate themomentum/energy of a particle beam 24 by assisting or controlling theconversion of inbound power from the one or more drivers 18 (e.g., RFpower) to kinetic energy imparted into the particles within the particlebeam 24. As described herein, the accelerator 10 can include one or morecavities 30 aligned along the particle beam 24 such that each cavity 30,being individually driven, can impart a substantial amount of energyinto the particle beam 24 thereby yielding a significant increase theoutput power of the particle beam 24. As each cavity 30 can berelatively compact and lightweight, a fully functional and accelerator10 can be designed and built with a relatively modest footprint in termsof size, weight, and power. In one variation of the accelerator 10 ofthe embodiment, the one or more cavities 30 can include more than tencavities 30. In another variation of the accelerator 10 of theembodiment, the one or more cavities 30 can include more than fifteencavities 30. In still another variation of the accelerator 10 of theembodiment, the one or more cavities 30 can include more than twentycavities 30. In another variation of the accelerator 10 of theembodiment, the one or more cavities 30 can include more thantwenty-five cavities 30. In still other variations of the accelerator 10of the embodiment, the one or more cavities 30 can include more than 30,more than 50, or more than 100 cavities. Particular example embodimentsdescribed herein illustrate two configurations with dozens of cavities30 that still provide for very compact and mobile operation of theaccelerator 10.

Cavities according to embodiments of the present invention may be anysuitable type of accelerator cavity.

As shown in FIG. 3, a cavity 30 can include a resonant cavity thatdefines a geometry within which an electric field can resonate, such asfor example an inbound electric field driven by the one or more drivers18. As shown in FIG. 3, a graphical overlay of electric field as afunction of distance illustrates a single wave resonant within thecavity 230, with a peak approximately in the middle of the cavity 230(e.g., in the middle of the cavity 230). The one or more cavities 230include a resonant cavity that resonates at approximately between 4 GHzand 6 GHz (e.g., between 4 GHz and 6 GHz). Alternatively, each of theone or more cavities 230 can include a picomotor piezo linear actuator250 that moves under the control of the frequency tuner 132. Thefunction of the picomotor piezo linear actuator 250 that is attached toouter part of the accelerator cavity wall 230 is to provide remote andreal-time adjustment of the resonance frequency of the acceleratorcavity 230. In another variation of the accelerator 10, each of the oneor more cavities 230 can include and/or define an accelerating gapdistance defined by a ratio of the velocity of a particle in theparticle beam 224 to the periodicity of the particle beam 224.

EXAMPLE CONFIGURATIONS

As also shown in FIG. 1, example configurations of the accelerator 10 ofthe embodiment, the one or more drivers 18 can include HEMT drivers,each providing a drive of approximately 370 W per cavity. A power outputper HEMT device as a function of time is shown in FIG. 4, wherein theaverage 370 W occurs at approximately 1×10⁻³ seconds. Given theforegoing, each of the one or more cavities 30 can be expected to addapproximately 20 keV of energy to the particle beam 24. As such,approximately fifty cavities 30 aligned in series will yield a 1 MeVparticle beam 24. An example electron beam pulse format is shown in FIG.5 for a representative output particle beam with a peak power ofapproximately 10 kW at 10% duty cycle. Accordingly, given a relativelylow input power of an example electron beam (10 kW) and a modest controlvoltage (50V power supply 20), given enough serially disposed cavities30 and high gain drivers 18, it is possible to generate a 1 MeV orgreater particle beam 24 from a lightweight accelerator with arelatively small physical footprint.

In another example embodiment of the accelerator 10, the power supply 20includes batteries or battery banks arranged in series to increase theDC voltage to the level needed to drive the RF drivers (for instance, abank of eight lithium batteries in series will provide 50 volts DC) thatpermit the accelerator 10 to be portable and usable in remote or rurallocations. FIGS. 6A and 6B are illustrative of the inherent tradeoffs insize, weight, and power that are current design constraints given thestate of the art in both battery technology and driver 18 gain. As shownin FIG. 6A, at or around 1 meter in overall length of the accelerator10, the weight per length tends to flatten out, with 2 kW/kg Li-ionbatteries adding relatively more weight to the overall device. However,those of skill in the art will readily note that even at 1.5 meters inlength, the heavier of the two battery configurations still weighs in ata relatively slight 45 kg, which is more than light enough to beassembled and deployed as a portable accelerator 10 in any number ofapplications. FIG. 6B illustrates various power/energy/weight curves fordifferent types of power sources on a logarithmic scale. The Li-ionpower sources of various kinds (very high power, high power, highenergy) display the greatest range. Those of skill in the art willappreciate that advances in either battery technology or drivertechnology, separately or together, can still further improve theperformance of accelerator 10 while keeping within the scope of thefundamental design parameters described herein.

FIGS. 7A and 7B are perspective views of alternative example embodimentsof the accelerator 10 of the embodiment. FIG. 7A illustrates an exampleaccelerator 300 that includes fifty five cavities and thirty lithiumbatteries arranged in series to provide 50V DC to power the RF driversto generate approximately a 1 MeV electron beam. The example accelerator300 is approximately 1.25 m in length along the axis and weighsapproximately 30 kg. FIG. 7B illustrates a second example accelerator400 that includes one hundred thirty eight cavities and eighty batteriesto generate approximately a 5 MeV electron beam. The second exampleaccelerator 400 is approximately 3.1 m in length along the axis andweighs approximately 108 kg. As illustrated in the exampleconfigurations, substantial power and portability can be readily devisedusing the principles set forth in describing the accelerator 10 of theembodiment and variations thereof. Such improvements in power andportability have the potential to greatly increase the availability andefficacy of medical technologies throughout all aspects of thepopulation, including especially those in remote and rural areas whohave been deprived of its benefit until the present invention.

The configurations shown in FIGS. 7A and 7B are for electron beams withtwo maximum energies (1 and 5 MeV). However, the configurations aresufficiently flexible to operate at energies below the maximum byturning off the HEMT drivers for certain accelerating cavities in orderto tune the electron beam energy to meet a specific application.

It will be understood that, although the terms “first,” “second,”“third,” etc., may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, a first element, component, region, layer or sectiondescribed below could be termed a second element, component, region,layer or section, without departing from the spirit and scope of thepresent invention.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to,” or “coupled to” another element or layer, itcan be directly on, connected to, or coupled to the other element orlayer, or one or more intervening elements or layers may be present. Inaddition, it will also be understood that when an element or layer isreferred to as being “between” two elements or layers, it can be theonly element or layer between the two elements or layers, or one or moreintervening elements or layers may also be present.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting of the present invention.As used herein, the singular forms “a” and “an” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and “including,” when used in thisspecification, specify the presence of the stated features, integers,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof. As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items. Expressions such as “at least one of,” whenpreceding a list of elements, modify the entire list of elements and donot modify the individual elements of the list.

As used herein, the term “substantially,” “about,” and similar terms areused as terms of approximation and not as terms of degree, and areintended to account for the inherent variations in measured orcalculated values that would be recognized by those of ordinary skill inthe art. Further, the use of “may” when describing embodiments of thepresent invention refers to “one or more embodiments of the presentinvention.” As used herein, the terms “use,” “using,” and “used” may beconsidered synonymous with the terms “utilize,” “utilizing,” and“utilized,” respectively. Also, the term “exemplary” is intended torefer to an example or illustration.

The electronic or electric devices (e.g., controllers) and/or any otherrelevant devices or components according to embodiments of the presentinvention described herein may be implemented utilizing any suitablehardware, firmware (e.g. an application-specific integrated circuit),software, or a combination of software, firmware, and hardware. Forexample, the various components of these devices may be formed on oneintegrated circuit (IC) chip or on separate IC chips. Further, thevarious components of these devices may be implemented on a flexibleprinted circuit film, a tape carrier package (TCP), a printed circuitboard (PCB), or formed on one substrate. Further, the various componentsof these devices may be a process or thread, running on one or moreprocessors, in one or more computing devices, executing computer programinstructions and interacting with other system components for performingthe various functionalities described herein. The computer programinstructions are stored in a memory which may be implemented in acomputing device using a standard memory device, such as, for example, arandom access memory (RAM). The computer program instructions may alsobe stored in other non-transitory computer readable media such as, forexample, a CD-ROM, flash drive, or the like. Also, a person of skill inthe art should recognize that the functionality of various computingdevices may be combined or integrated into a single computing device, orthe functionality of a particular computing device may be distributedacross one or more other computing devices without departing from thespirit and scope of the exemplary embodiments of the present invention.

While this invention has been described in detail with particularreferences to and illustrative embodiments thereof, the embodimentsdescribed herein are not intended to be exhaustive or to limit the scopeof the invention to the exact forms disclosed. Persons skilled in theart and technology to which this invention pertains will appreciate thatalterations and changes in the described structures and methods ofassembly and operation can be practiced without meaningfully departingfrom the principles, spirit, and scope of this invention, as set forthin the following claims and equivalents thereof.

What is claimed is:
 1. A particle accelerator comprising: two or morecavities disposed along an axis of the particle accelerator andconfigured to be driven independently by solid-state transistor radiofrequency (RF) sources; two or more independent RF drivers, each withits own phase and amplitude control, independent of the other RFdrivers; a low-voltage power supply configured to provide power to thetwo or more RF drivers; and a frequency tuner configured to adjustresonance frequencies of the two or more cavities, wherein each of thetwo or more cavities comprises a linear actuator configured to moveunder control of the frequency tuner to provide remote and real timeadjustment of the resonant frequency of the cavity.
 2. The particleaccelerator of claim 1, wherein each of the two or more RF driverscomprises a high electron mobility transistor (HEMT).
 3. The particleaccelerator of claim 2, wherein each of the two or more RF driversfurther comprises a phase shifter coupled to the HEMT.
 4. The particleaccelerator of claim 1, wherein each of the two or more RF drivers isconfigured to drive between 300 W and 500 W of RF power to each of thetwo or more cavities.
 5. The particle accelerator of claim 1, whereineach of the two or more RF drivers is configured to drive more than 300W of power to each of the two or more cavities.
 6. The particleaccelerator of claim 1, wherein each of the two or more RF drivers isconfigured to drive between 200 W and 400 W of RF power to each of thetwo or more cavities.
 7. The particle accelerator of claim 1, whereineach of the two or more RF drivers is configured to drive at least 350 Wand 400 W of RF power to each of the two or more cavities.
 8. Theparticle accelerator of claim 1, wherein the power supply comprises oneor more batteries.
 9. The particle accelerator of claim 1, wherein thepower supply comprises commercial power provided through a wall outlet.10. The particle accelerator of claim 1, wherein the two or morecavities comprise more than ten cavities.
 11. The particle acceleratorof claim 1, wherein the two or more cavities comprise more than fifteencavities.
 12. The particle accelerator of claim 1, wherein the two ormore cavities comprise more than twenty cavities.
 13. The particleaccelerator of claim 1, wherein the two or more cavities comprise morethan twenty-five cavities.
 14. The particle accelerator of claim 1,wherein each of the two or more cavities comprises a resonant cavityconfigured to resonate between 1 GHz and 6 GHz.
 15. The particleaccelerator of claim 1, wherein each of the two or more cavitiescomprises a resonant cavity configured to resonate at 5.1 GHz.
 16. Theparticle accelerator of claim 1, wherein each of the two or morecavities comprises an accelerating gap distance defined by a ratio of avelocity of a particle in a particle beam to speed of light.
 17. Aparticle accelerator comprising: two or more cavities disposed along anaxis of the particle accelerator and configured to be drivenindependently by solid-state transistor radio frequency (RF) sources;two or more independent RF drivers, each with its own phase andamplitude control, independent of the other RF drivers; and alow-voltage power supply configured to provide power to the two or moreRF drivers, wherein the two or more cavities comprise fifty fivecavities and the power supply comprises thirty batteries, and the fiftyfive cavities and the thirty batteries are configured to generate a 1MeV electron beam along the axis of the particle accelerator.
 18. Theparticle accelerator of claim 17, wherein the particle accelerator is1.25 m in length along the axis of the particle accelerator and weighs30 kg.
 19. A particle accelerator comprising: two or more cavitiesdisposed along an axis of the particle accelerator and configured to bedriven independently by solid-state transistor radio frequency (RF)sources; two or more independent RF drivers, each with its own phase andamplitude control, independent of the other RF drivers; and alow-voltage power supply configured to provide power to the two or moreRF drivers, wherein the two or more cavities comprise one hundred thirtyeight cavities and the power supply comprises seventy-five batteries,and the one hundred thirty eight cavities and the seventy-five batteriesare configured to generate a 5 MeV electron beam.
 20. The particleaccelerator of claim 19, wherein the particle accelerator is 3.1 m inlength along the axis of the particle accelerator and weighs 108 kg. 21.A particle accelerator comprising: three or more cavities disposed alongan axis of the particle accelerator and configured to be drivenindependently by solid-state transistor radio frequency (RF) sources;two or more independent RF drivers, each with its own phase andamplitude control, independent of the other RF drivers; a thirdindependent RF driver without its own phase control; and a low-voltagepower supply configured to provide power to the two or more RF driversand the third RF driver; and a frequency tuner configured to adjustresonance frequencies of the two or more cavities, wherein each of thetwo or more cavities comprises a linear actuator configured to moveunder control of the frequency tuner to provide remote and real timeadjustment of the resonant frequency of the cavity.